Cloned DNA sequences that determine mRNA stability of bacteriophage ФX174in vivoare functional

Abstract
The stability of two species of øx174 polycistronio mRNA in vivo can be altered by mutating sequences existing immediately upstream of a termination site. The wild type phage contains an mRNA stabilixing sequence ((+) sequence), while the same sequence mutated by insertion ((−) sequence) reduces the stability of the mRNAs. These two sequences were cloned at the 3′ ends of gene D or gene B of øX174 in a pBR322 derivative plasmid. The cloned sequences were functional. The (+) sequence stabilized gene B or gene D mRNA; half-lives of these mRNAs were 7 to 8 min. When the (+) sequence is eliminated ((o) sequence) or replaced with the (−) sequence, the half-lives of the mRNA were reduced to about 1 to 2 min. The stabilisation of mRNAs caused an increased production of these proteins.